Elvis Aron Presley, the aging messiah of rock music, descended from his hermetically sealed hotel room in St. Louis last night to perform in Kiel auditorium an imitation of swivel-hipped Elvis Presley circa 1956.

He enthralled the masses with his imitation. Plumplish women over 30 in the audience of about 14,000 were observed to be squealing and squirming in their seats as the former truck driver from Memphis plunked his guitar, wiggled his hips and howled old songs, such as "You Ain't Nothin' But a Hown Dawn," in between gasps for breath. Many cheered for the myth, if not for the man.

Elvis's actions and songs were carefully programmed last night to feed the myth. In older days, he was the unaffected country boy. Born in Faulner country around Tupelo, Miss., he moved to Memphis, drove a truck for an electrical company, made him some records for the Sun Record Co. and became an overnight sensation with the pubescent populace in America.

Aloof From Fans

Elvis used to mingle with his fans and talk with the press, but yesterday he was sequestered in the Chase-Park Plaza until almost stage time. He came to St. Louis from Phoenix, where he faced more than 15,000 persons, his first mass audience since 1958.

Parts of that show were filmed for an MGM documentary movie, "Elvis," dealing with old Mr. Rock 'n' Roll, his manager, "Colonel" Tom Parker, and their rise to fame.

Elvis came with his entourage on three chartered jet planes. He stayed locked up at the hotel (two floors were reserved for the musician and his troupe).

Parker rebuffed attempts by MGM officers to arrange press interviews with Elvis. A New York City promoter of the St. Louis concert refused to say how much money Elvis was earning.

"Elvis and the colonel are happy with it (the amount), the promoter said.

Parker, a veteran showman who formerly rented elephants in Las Vegas before he took over management of Elvis in 1956, was apparently keeping his boy from overexposure. Press photographers had to purchase tickets to get into the concert last night. The messiah of rock music was well protected and his display was brief.

Elvis came on stage at 9:31 p.m. He sang 17 songs and rushed off at 10:20, soaked with sweat and minus a crimson neck scarf. He had more than, two dozen singers and instrumentalists behind him.

What happened while he performed might be compared to an overstaged version of a Hollywood production of the Old Testament.

In Elvis's case, the audience was warmed up by a slickly slick stand-up comic, some young back girl singers and a big, loud orchestra, aided by some guitar pickers.

Elvis, 35 years old, rushed on stage with his hair dyed black, his trimmed down body clothed in pure white with bellbottom trousers and white shoed and the crimson neck scarf that he tossed to a girl in the audience massed in back of burly bodyguards standing at the foot of the stage.

Elvis's baritone was reasonably resonant, but one couldn't tell if he was on key because of the shouts from the audience and the electrified music. But it really didn't matter about his voice.